/**
* MD5算法
*/

#ifndef __CTLIB_MD5_H__
#define __CTLIB_MD5_H__

#include <string.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/types.h>

#define MD5_DIGEST_SIZE 16
#define MD5_BLOCK_SIZE 64

#ifndef __GNUC_PREREQ
# if defined __GNUC__ && defined __GNUC_MINOR__
#  define __GNUC_PREREQ(maj, min)                                       \
    ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
# else
#  define __GNUC_PREREQ(maj, min) 0
# endif
#endif

#ifndef _LIBC
# define __md5_buffer md5_buffer
# define __md5_finish_ctx md5_finish_ctx
# define __md5_init_ctx md5_init_ctx
# define __md5_process_block md5_process_block
# define __md5_process_bytes md5_process_bytes
# define __md5_read_ctx md5_read_ctx
# define __md5_stream md5_stream
#endif

#if USE_UNLOCKED_IO
# include "unlocked-io.h"
#endif

#ifdef _LIBC
# include <endian.h>
# if __BYTE_ORDER == __BIG_ENDIAN
#  define WORDS_BIGENDIAN 1
# endif
/* We need to keep the namespace clean so define the MD5 function
   protected using leading __ .  */
#endif

#ifdef WORDS_BIGENDIAN
# define SWAP(n)                                                        \
    (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
#else
# define SWAP(n) (n)
#endif

#define BLOCKSIZE 32768
#if BLOCKSIZE % 64 != 0
# error "invalid BLOCKSIZE"
#endif

static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };

# ifdef __cplusplus
extern "C" {
# endif



# ifdef __cplusplus
}
# endif

namespace CTLib
{

class CTMD5
{
public:
        /* Structure to save state of computation between the single steps.  */
    struct ctlib_md5_ctx
    {
      uint32_t A;
      uint32_t B;
      uint32_t C;
      uint32_t D;

      uint32_t total[2];
      uint32_t buflen;
      uint32_t buffer[32];
    };

    /*
     * The following three functions are build up the low level used in
     * the functions 'md5_stream' and 'md5_buffer'.
     */

    /* Initialize structure containing state of computation.
       (RFC 1321, 3.3: Step 3)  */
    static inline void
    ctlib_md5_init_ctx (struct ctlib_md5_ctx *ctx)
    {
      ctx->A = 0x67452301;
      ctx->B = 0xefcdab89;
      ctx->C = 0x98badcfe;
      ctx->D = 0x10325476;

      ctx->total[0] = ctx->total[1] = 0;
      ctx->buflen = 0;
    }

    /* Copy the 4 byte value from v into the memory location pointed to by *cp,
       If your architecture allows unaligned access this is equivalent to
       * (uint32_t *) cp = v  */
    static inline void
    set_uint32 (char *cp, uint32_t v)
    {
      memcpy (cp, &v, sizeof v);
    }

    /* These are the four functions used in the four steps of the MD5 algorithm
       and defined in the RFC 1321.  The first function is a little bit optimized
       (as found in Colin Plumbs public domain implementation).  */
    /* #define FF(b, c, d) ((b & c) | (~b & d)) */
    #define FF(b, c, d) (d ^ (b & (c ^ d)))
    #define FG(b, c, d) FF (d, b, c)
    #define FH(b, c, d) (b ^ c ^ d)
    #define FI(b, c, d) (c ^ (b | ~d))

    /* Process LEN bytes of BUFFER, accumulating context into CTX.
       It is assumed that LEN % 64 == 0.  */

    static void
    ctlib_md5_process_block (const void *buffer, size_t len, struct ctlib_md5_ctx *ctx)
    {
      uint32_t correct_words[16];
      const uint32_t *words = (const uint32_t *)buffer;
      size_t nwords = len / sizeof (uint32_t);
      const uint32_t *endp = words + nwords;
      uint32_t A = ctx->A;
      uint32_t B = ctx->B;
      uint32_t C = ctx->C;
      uint32_t D = ctx->D;
      uint32_t lolen = len;

      /* First increment the byte count.  RFC 1321 specifies the possible
         length of the file up to 2^64 bits.  Here we only compute the
         number of bytes.  Do a double word increment.  */
      ctx->total[0] += lolen;
      ctx->total[1] += (len >> 31 >> 1) + (ctx->total[0] < lolen);

      /* Process all bytes in the buffer with 64 bytes in each round of
         the loop.  */
      while (words < endp)
        {
          uint32_t *cwp = correct_words;
          uint32_t A_save = A;
          uint32_t B_save = B;
          uint32_t C_save = C;
          uint32_t D_save = D;

          /* First round: using the given function, the context and a constant
             the next context is computed.  Because the algorithms processing
             unit is a 32-bit word and it is determined to work on words in
             little endian byte order we perhaps have to change the byte order
             before the computation.  To reduce the work for the next steps
             we store the swapped words in the array CORRECT_WORDS.  */

    #define OP(a, b, c, d, s, T)                                            \
          do                                                                \
            {                                                               \
              a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T;             \
              ++words;                                                      \
              CYCLIC (a, s);                                                \
              a += b;                                                       \
            }                                                               \
          while (0)

          /* It is unfortunate that C does not provide an operator for
             cyclic rotation.  Hope the C compiler is smart enough.  */
    #define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))

          /* Before we start, one word to the strange constants.
             They are defined in RFC 1321 as

             T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64

             Here is an equivalent invocation using Perl:

             perl -e 'foreach(1..64){printf "0x%08x\n", int (4294967296 * abs (sin $_))}'
           */

          /* Round 1.  */
          OP (A, B, C, D, 7, 0xd76aa478);
          OP (D, A, B, C, 12, 0xe8c7b756);
          OP (C, D, A, B, 17, 0x242070db);
          OP (B, C, D, A, 22, 0xc1bdceee);
          OP (A, B, C, D, 7, 0xf57c0faf);
          OP (D, A, B, C, 12, 0x4787c62a);
          OP (C, D, A, B, 17, 0xa8304613);
          OP (B, C, D, A, 22, 0xfd469501);
          OP (A, B, C, D, 7, 0x698098d8);
          OP (D, A, B, C, 12, 0x8b44f7af);
          OP (C, D, A, B, 17, 0xffff5bb1);
          OP (B, C, D, A, 22, 0x895cd7be);
          OP (A, B, C, D, 7, 0x6b901122);
          OP (D, A, B, C, 12, 0xfd987193);
          OP (C, D, A, B, 17, 0xa679438e);
          OP (B, C, D, A, 22, 0x49b40821);

          /* For the second to fourth round we have the possibly swapped words
             in CORRECT_WORDS.  Redefine the macro to take an additional first
             argument specifying the function to use.  */
    #undef OP
    #define OP(f, a, b, c, d, k, s, T)                                      \
          do                                                                \
            {                                                               \
              a += f (b, c, d) + correct_words[k] + T;                      \
              CYCLIC (a, s);                                                \
              a += b;                                                       \
            }                                                               \
          while (0)

          /* Round 2.  */
          OP (FG, A, B, C, D, 1, 5, 0xf61e2562);
          OP (FG, D, A, B, C, 6, 9, 0xc040b340);
          OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
          OP (FG, B, C, D, A, 0, 20, 0xe9b6c7aa);
          OP (FG, A, B, C, D, 5, 5, 0xd62f105d);
          OP (FG, D, A, B, C, 10, 9, 0x02441453);
          OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
          OP (FG, B, C, D, A, 4, 20, 0xe7d3fbc8);
          OP (FG, A, B, C, D, 9, 5, 0x21e1cde6);
          OP (FG, D, A, B, C, 14, 9, 0xc33707d6);
          OP (FG, C, D, A, B, 3, 14, 0xf4d50d87);
          OP (FG, B, C, D, A, 8, 20, 0x455a14ed);
          OP (FG, A, B, C, D, 13, 5, 0xa9e3e905);
          OP (FG, D, A, B, C, 2, 9, 0xfcefa3f8);
          OP (FG, C, D, A, B, 7, 14, 0x676f02d9);
          OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);

          /* Round 3.  */
          OP (FH, A, B, C, D, 5, 4, 0xfffa3942);
          OP (FH, D, A, B, C, 8, 11, 0x8771f681);
          OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
          OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
          OP (FH, A, B, C, D, 1, 4, 0xa4beea44);
          OP (FH, D, A, B, C, 4, 11, 0x4bdecfa9);
          OP (FH, C, D, A, B, 7, 16, 0xf6bb4b60);
          OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
          OP (FH, A, B, C, D, 13, 4, 0x289b7ec6);
          OP (FH, D, A, B, C, 0, 11, 0xeaa127fa);
          OP (FH, C, D, A, B, 3, 16, 0xd4ef3085);
          OP (FH, B, C, D, A, 6, 23, 0x04881d05);
          OP (FH, A, B, C, D, 9, 4, 0xd9d4d039);
          OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
          OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
          OP (FH, B, C, D, A, 2, 23, 0xc4ac5665);

          /* Round 4.  */
          OP (FI, A, B, C, D, 0, 6, 0xf4292244);
          OP (FI, D, A, B, C, 7, 10, 0x432aff97);
          OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
          OP (FI, B, C, D, A, 5, 21, 0xfc93a039);
          OP (FI, A, B, C, D, 12, 6, 0x655b59c3);
          OP (FI, D, A, B, C, 3, 10, 0x8f0ccc92);
          OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
          OP (FI, B, C, D, A, 1, 21, 0x85845dd1);
          OP (FI, A, B, C, D, 8, 6, 0x6fa87e4f);
          OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
          OP (FI, C, D, A, B, 6, 15, 0xa3014314);
          OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
          OP (FI, A, B, C, D, 4, 6, 0xf7537e82);
          OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
          OP (FI, C, D, A, B, 2, 15, 0x2ad7d2bb);
          OP (FI, B, C, D, A, 9, 21, 0xeb86d391);

          /* Add the starting values of the context.  */
          A += A_save;
          B += B_save;
          C += C_save;
          D += D_save;
        }

      /* Put checksum in context given as argument.  */
      ctx->A = A;
      ctx->B = B;
      ctx->C = C;
      ctx->D = D;
    }

    static void
    ctlib_md5_process_bytes (const void *buffer, size_t len, struct ctlib_md5_ctx *ctx)
    {
      /* When we already have some bits in our internal buffer concatenate
         both inputs first.  */
      if (ctx->buflen != 0)
        {
          size_t left_over = ctx->buflen;
          size_t add = 128 - left_over > len ? len : 128 - left_over;

          memcpy (&((char *) ctx->buffer)[left_over], buffer, add);
          ctx->buflen += add;

          if (ctx->buflen > 64)
            {
              ctlib_md5_process_block (ctx->buffer, ctx->buflen & ~63, ctx);

              ctx->buflen &= 63;
              /* The regions in the following copy operation cannot overlap.  */
              memcpy (ctx->buffer,
                      &((char *) ctx->buffer)[(left_over + add) & ~63],
                      ctx->buflen);
            }

          buffer = (const char *) buffer + add;
          len -= add;
        }

      /* Process available complete blocks.  */
      if (len >= 64)
        {
    #if !_STRING_ARCH_unaligned
    # define UNALIGNED_P(p) ((uintptr_t) (p) % __alignof__ (uint32_t) != 0)
          if (UNALIGNED_P (buffer))
            while (len > 64)
              {
                ctlib_md5_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
                buffer = (const char *) buffer + 64;
                len -= 64;
              }
          else
    #endif
            {
              ctlib_md5_process_block (buffer, len & ~63, ctx);
              buffer = (const char *) buffer + (len & ~63);
              len &= 63;
            }
        }

      /* Move remaining bytes in internal buffer.  */
      if (len > 0)
        {
          size_t left_over = ctx->buflen;

          memcpy (&((char *) ctx->buffer)[left_over], buffer, len);
          left_over += len;
          if (left_over >= 64)
            {
              ctlib_md5_process_block (ctx->buffer, 64, ctx);
              left_over -= 64;
              memcpy (ctx->buffer, &ctx->buffer[16], left_over);
            }
          ctx->buflen = left_over;
        }
    }

    /* Put result from CTX in first 16 bytes following RESBUF.  The result
       must be in little endian byte order.  */
    static void *
    ctlib_md5_read_ctx (const struct ctlib_md5_ctx *ctx, void *resbuf)
    {
      char *r = (char*)resbuf;
      set_uint32 (r + 0 * sizeof ctx->A, SWAP (ctx->A));
      set_uint32 (r + 1 * sizeof ctx->B, SWAP (ctx->B));
      set_uint32 (r + 2 * sizeof ctx->C, SWAP (ctx->C));
      set_uint32 (r + 3 * sizeof ctx->D, SWAP (ctx->D));

      return resbuf;
    }

    /* Process the remaining bytes in the internal buffer and the usual
       prolog according to the standard and write the result to RESBUF.  */
    static void *
    ctlib_md5_finish_ctx (struct ctlib_md5_ctx *ctx, void *resbuf)
    {
      /* Take yet unprocessed bytes into account.  */
      uint32_t bytes = ctx->buflen;
      size_t size = (bytes < 56) ? 64 / 4 : 64 * 2 / 4;

      /* Now count remaining bytes.  */
      ctx->total[0] += bytes;
      if (ctx->total[0] < bytes)
        ++ctx->total[1];

      /* Put the 64-bit file length in *bits* at the end of the buffer.  */
      ctx->buffer[size - 2] = SWAP (ctx->total[0] << 3);
      ctx->buffer[size - 1] = SWAP ((ctx->total[1] << 3) | (ctx->total[0] >> 29));

      memcpy (&((char *) ctx->buffer)[bytes], fillbuf, (size - 2) * 4 - bytes);

      /* Process last bytes.  */
      ctlib_md5_process_block (ctx->buffer, size * 4, ctx);

      return ctlib_md5_read_ctx (ctx, resbuf);
    }


    /* Compute MD5 message digest for bytes read from STREAM.  The
       resulting message digest number will be written into the 16 bytes
       beginning at RESBLOCK.  */
    static int
    md5_stream (FILE *stream, void *resblock)
    {
      struct ctlib_md5_ctx ctx;
      size_t sum;

      char *buffer = (char*)malloc (BLOCKSIZE + 72);
      if (!buffer)
        return 1;

      /* Initialize the computation context.  */
      ctlib_md5_init_ctx (&ctx);

      /* Iterate over full file contents.  */
      while (1)
        {
          /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
             computation function processes the whole buffer so that with the
             next round of the loop another block can be read.  */
          size_t n;
          sum = 0;

          /* Read block.  Take care for partial reads.  */
          while (1)
            {
              n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);

              sum += n;

              if (sum == BLOCKSIZE)
                break;

              if (n == 0)
                {
                  /* Check for the error flag IFF N == 0, so that we don't
                     exit the loop after a partial read due to e.g., EAGAIN
                     or EWOULDBLOCK.  */
                  if (ferror (stream))
                    {
                      free (buffer);
                      return 1;
                    }
                  goto process_partial_block;
                }

              /* We've read at least one byte, so ignore errors.  But always
                 check for EOF, since feof may be true even though N > 0.
                 Otherwise, we could end up calling fread after EOF.  */
              if (feof (stream))
                goto process_partial_block;
            }

          /* Process buffer with BLOCKSIZE bytes.  Note that
             BLOCKSIZE % 64 == 0
           */
          ctlib_md5_process_block (buffer, BLOCKSIZE, &ctx);
        }

    process_partial_block:

      /* Process any remaining bytes.  */
      if (sum > 0)
        ctlib_md5_process_bytes (buffer, sum, &ctx);

      /* Construct result in desired memory.  */
      ctlib_md5_finish_ctx (&ctx, resblock);
      free (buffer);
      return 0;
    }

    /* Compute MD5 message digest for LEN bytes beginning at BUFFER.  The
       result is always in little endian byte order, so that a byte-wise
       output yields to the wanted ASCII representation of the message
       digest.  */
    static void *
    md5_buffer (const char *buffer, size_t len, void *resblock)
    {
      struct ctlib_md5_ctx ctx;

      /* Initialize the computation context.  */
      ctlib_md5_init_ctx (&ctx);

      /* Process whole buffer but last len % 64 bytes.  */
      ctlib_md5_process_bytes (buffer, len, &ctx);

      /* Put result in desired memory area.  */
      return ctlib_md5_finish_ctx (&ctx, resblock);
    }

    static const char* GetMD5(const char* pszBuf, int iBufLen)
    {
        unsigned char md[16];
        char temp[3] = {'\0'};
        static char ans[100];
        ans[0] = '\0';
        __md5_buffer(pszBuf, iBufLen, (char*)md);
        for(int i=0; i<16; i++)
        {
            sprintf(temp, "%02x", md[i]);
            strcat(ans, temp);
        }
        return ans;
    }
};

} // namespace

#endif //__CTLIB_MD5_H__
